Two out of 3.
Everyone knows that smoking is bad for the human body. But what if your doctor told you that 2 out of 3 smokers will go to an early grave because of it?
A new study from researchers at the Australian National University's National Centre for Epidemiology and Population Health paints a grim picture of the tobacco industry. The research, published in full at BMC Medicine, projects that 1.8 million of Australia's 2.7 million smokers, or roughly two-thirds, will perish from causes that can be directly attributed to their tobacco habit.
Just 1 in 3 smokers will live long enough to die from something else.
The science: To reach these conclusions, the scientists tracked 204,953 individuals aged 45 or older who participated in the Sax Institute's 45 and Up Study. The researchers controlled for various factors such as higher body mass index and elevated levels of drinking, as well as lower rates of education, income and health insurance coverage.
From 2006 to 2009, 5,593 of the participants died. When other factors were controlled for, the team found smokers were nearly three times more likely to die over that three-year period than someone who never picked up a cigarette. People who smoked more than 25 cigarettes a day (one pack) had around four times the relative risk of dying. Former smokers fared much better, with about 1.3 times the relative risk of mortality as the general population.
When the researchers applied those numbers to Australia's 2.7 million smokers, they reached the conclusion that 1.8 million of them will eventually die from complications related to tobacco consumption. These include everything from heart disease to lung cancer, as well as higher risks of infection.
"The two-thirds attributable fraction (i.e., two-thirds of smokers will eventually be killed by their smoking) is exactly in line with similar large-scale cohort studies in the U.K. and the USA. It confirms exactly that if Australians smoke like the British and Americans, they will die like them," lead investigator Alan D. Lopez of the University of Melbourne told Mic via email. "Our study follows very similar methodology to previous large-scale prospective studies, so [it's] unlikely we overlooked/exaggerated anything."
"We estimate that smokers, on average, die 10 years earlier than lifelong non-smokers," he added, pointing to Figure 5 from the report:
Lopez also pointed out that smokers don't just die earlier — their lives are "significantly" worse thanks to elevated rates of painful, long-term illnesses.
"Our study looked at mortality only. We do have quality of life data for our cohort and we are analyzing that information, but do not expect to have results for some time," he said. "I fully expect that smokers will have significantly worse quality of life than non-smokers. For example, many smokers only die from emphysema after a long and very debilitating illness."
What about smoking less? Self-declared "light smokers" are likely unaware of the risk even just a few cigarettes poses.
"It is my general impression that many people underestimate the risks relating to smoking, especially those who consider themselves 'light smokers,'" professor Emily Banks, scientific director of the Sax Institute's study, told Mic.
"I've also heard people say that they are otherwise fit and have a good diet, so smoking is just one vice and they are generally healthy. We found that the risks of dying during the follow up period were doubled in people smoking 14 or fewer cigarettes per day, indicating that the risks are substantial. They are also not offset by diet or physical activity."
Why you should care: Doctors have known since the 1956 British Doctors' Study that smoking is one of the most destructive personal habits someone can pick up, but the two-thirds statistic is another reminder that by taking up tobacco, people are gambling with their lives. According to Healthline, more than 60% of people who have ever begun smoking daily meet the criterion for nicotine dependence.
Once they get there, it can be very difficult to stop. The CDC reports that just short of 70% of American adult smokers want to quit, while 42.7% had made an attempt to quit in the past year. Non-smokers should realize that this party is easy to get into, but hard to leave.
"The implications of our research are very clear: Tobacco is still a major cause of premature mortality in Australia and will continue to be so unless Australian tobacco control policy can push smoking prevalence way down below 10%. It is around 15% currently," Lopez told Mic. "Australia is at the forefront of global tobacco control efforts, and that bold policy response has been greatly influenced, in my view, by the evidence about tobacco hazards."
As Lopez says, Australia has some of the harshest anti-smoking campaigns in the world with extremely strict tobacco-marketing rules. With numbers as startling as 2 out of 3, maybe the message of smoking's extreme dangers will finally be heard.
Or as Banks more bluntly put it: "Moves towards tobacco eradication would also be appropriate."
Updated: March 4, 2014, 6:13 pm